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COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division Rationale - Page 3. Permit No. CO-0026981 FACILITY DESCRIPTION: (Continued) The facility is an underground gold and silver mine with a surface mill facility. The primary product, gold, will be mined at 500 ounces per day from 500 tons of rock per day. Previously, the primary products mined included lead, zinc and copper; however, although presently these metals do occur, they are not significant products. Discharges are projected to continue occurring throughout the lifetime of the mine for the next 50 years. APPLICABLE RULES AND REGULATIONS: Federal technology based effluent limitations (BAT and BPT) are applicable to this facility because mining and milling will be taking place. State effluent standards (SES) and instream water quality standards (WQS) are also applicable. Table I shows a comparison of the applicable state and federal limitations. Table I Applicable Limitations Parameter BAT/BPT SES WQS Total Suspended Solids, mg/1 20/30 30/45 N/A pH, s.u. 6.0 - 9.0 6.0 - 9.0 6.5 - 9.0 Oil and Grease, mg/1 N/A 10.0 N/A Cadmium, mg/1 0.05 /0.10 N/A 0.0012 Copper, mg/1 0.15 /0.30 N/A 0.012 Lead, mg/1 0.3 /0.6 N/A 0.008 Mercury, mg/1 0.001/0.002 N/A 0.00005 Zinc, mg/1 0.50 (1.0 N(A 0.3 Boron, mg/1 N/A N/A 0.75 Cyanide (free), mg/1 N/A N/A 0.005 Arsenic, mg/1 N/A N/A 0.05 Chromium (tri), mg/1 N/A N/A 0.1 Chromium (hex), mg/1 N/A N/A 0.025 Nickel, mg/1 N/A N/A 0.05 Selenium, mg/1 N/A N/A 0.02 Silver, mg/1 N/A N/A 0.0001 Iron (total), mg/1 N/A N/A 1.0 Manganese (total), mg/1 N/A N/A 1.0 EFFLUENT LIMITATIONS, RATIONALE, AND MONITORING FREQUEtdCIES: The BAT limitations for gold mines of 20/30 mg/1 for total suspended solids (TSS) are applicable to this facility's discharge. The state effluent standard for oil and grease of 10 mg/1 is the basis for this limitation. The other limitations are based on state water quality standards for Segment 9.